Problem with decrementer interrupt

Tue Feb 24 22:53:13 EST 2009

The reason that i m using bla is that i am writing the interrupt
handler from dec_start: to dec_end:....
then i am relocating this code to its corresponding vector
location(0x900)...As this relocated code is gonna be executed on
occurrence of interrupt, i cant use bl instruction...i have to go for
bla...
The C code is getting executed for sure...hav checked this using some
debug message...But the return from that function is not
happening...somehow the link register is not getting properly
loaded...dont knw wat is the reason behind this...

Regards,
Sumedh

On Tue, Feb 24, 2009 at 1:24 PM, sjoyeau at wanadoo.fr <sjoyeau at wanadoo.fr> wrote:
> Sumedh,
>
> I've just noticed you are using the "bla" instruction, which use absolute
> target address: are you sure the C code gets even be executed ?
> I don't know how the compiler successfully assemble your code because the
> binary is supposed to be position independant code (PIC): you should rather
> use "bl" instruction (relative branch).
>
> --
> sj
>
> 2009/2/23 sumedh tirodkar <sumedhtirodkar at gmail.com>
>>
>> I have initialised to stack pointer(r1) properly...actually...i went
>> thru the object dump...bt when i juz use
>>
>>  bla <function_name_handler>
>>
>> the link register is not getting pushed on to the stack in the prolog
>> of that function...so the stack is basically not coming into the
>> picture...
>> @IRQ originator, that doesn't seem to be a problem...
>>
>> The only thing that i am able to think of is that when i do a "bla",
>> the return address is not getting stored in link register...and i m
>> not able to figure out why...
>>
>> Regards,
>> Sumedh
>>
>> On Mon, Feb 23, 2009 at 11:03 PM, sjoyeau at wanadoo.fr <sjoyeau at wanadoo.fr>
>> wrote:
>> > Hi Sumedh,
>> >
>> > You may check the context in which your CPU in running the C code from
>> > interrupt context (ie stack pointer (r1), kernel locks disabling
>> > rescheduling etc..) and double check the IRQ originator (the
>> > decrementer) is
>> > acknowlegded somewhere your handler before enabling back interrupts,
>> > else
>> > your handler gets fired.
>> >
>> > --
>> > sj
>> >
>> > 2009/2/23 sumedh tirodkar <sumedhtirodkar at gmail.com>
>> >>
>> >> Alright...I am trying to develop a system of my own..
>> >> Consider that i am not using any linux kernel...I m writing some
>> >> program right from scratch.........
>> >> The major steps that i have taken are...
>> >>
>> >> 1. Started with a assembly file...
>> >> 2. Have relocated the interrupt handlers to there respective
>> >> positions...The interrupt handlers are written in assembly language...
>> >> 3. Initialised Decrementer register to get an interrupt after some
>> >> interval...
>> >> 4. Jump to some function using
>> >>
>> >>    bl <function_name_main>
>> >>
>> >>    function_name_main which will have a infinite while loop..
>> >> This works fine i.e. the interrupts(decrementer interrupt to be more
>> >> specific) work fine...I have initialised serial port to get the
>> >> output...
>> >>
>> >> Now, the problem that i am facing....
>> >>
>> >> If in interrupt handler of the decrementer, i make a call to some C
>> >> function in some other C file...using the follwing statement...
>> >>
>> >> Dec_handler:  /* I have relocated this to interrupt vector address of
>> >> decrementer interrupt*/
>> >>     /*code to print using serial port*/
>> >>     bla <function_name_handler> /*code to call some function in C
>> >> file*/
>> >>     /*code to print using serial port---but i m never able to see this
>> >> output*/
>> >>     RFI
>> >>
>> >> This starts creating a problem...somehow we dont return to this code
>> >> after the end of the function_name_handler...
>> >> Consider the following code for the function_name_handler:
>> >> void function_name_handler(void)
>> >> {
>> >>   /*Some action*/
>> >> }
>> >>
>> >> So, if its possible for anyone to help me with this...please reply...
>> >>
>> >> Regards,
>> >> Sumedh
>> >>
>> >>
>> >> On Mon, Feb 23, 2009 at 8:18 PM, Matt Gessner <mgessner at gmail.com>
>> >> wrote:
>> >> >
>> >> >
>> >> > On Mon, Feb 23, 2009 at 8:03 AM, sumedh tirodkar
>> >> > <sumedhtirodkar at gmail.com>
>> >> > wrote:
>> >> >>
>> >> >> I am using PowerPC 7447A...I am trying to port SA-RTL on PowerPC...
>> >> >
>> >> > What I said earlier was: You need to tell people what cpu you're
>> >> > using,
>> >> > what
>> >> > linux kernel, etc etc etc.
>> >> >
>> >> > Fine, we know the CPU.  What kernel are you using?  Is it ancient?
>> >> >
>> >> > I doubt the information below is going to be useful...
>> >> >
>> >> >>
>> >> >> I am using
>> >> >>
>> >> >> bla <function_name>
>> >> >>
>> >> >> from the assembly code to call the function in C file...This i am
>> >> >> doing from interrupt handler of the decrementer...
>> >> >> If any more details are required, please let me know...
>> >> >
>> >> >
>> >> _______________________________________________
>> >> Linuxppc-dev mailing list
>> >> Linuxppc-dev at ozlabs.org
>> >> https://ozlabs.org/mailman/listinfo/linuxppc-dev
>> >
>> >
>> >
>> > --
>> > ------------------
>> > Sylvain JOYEAU
>> > Freelance Engineer
>> > Software RT-OS R&D
>> > sylvain.joyeau at gmail.com
>> > Tél: +33-(0)667 477 052
>> > "A good idea is one side of the coin. The other side is the practical
>> > usefulness". J. Liedke.
>> >
>>
>>
>
>
>
> --
> ------------------
> Sylvain JOYEAU
> Freelance Engineer
> Software RT-OS R&D
> sylvain.joyeau at gmail.com
> Tél: +33-(0)667 477 052
> "A good idea is one side of the coin. The other side is the practical
> usefulness". J. Liedke.
>